CVE-2016-2182 in OpenSSL
Summary
by MITRE
The BN_bn2dec function in crypto/bn/bn_print.c in OpenSSL before 1.1.0 does not properly validate division results, which allows remote attackers to cause a denial of service (out-of-bounds write and application crash) or possibly have unspecified other impact via unknown vectors.
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Analysis
by VulDB Data Team • 08/29/2024
The vulnerability identified as CVE-2016-2182 resides within the OpenSSL cryptographic library, specifically within the BN_bn2dec function located in the crypto/bn/bn_print.c file. This function is responsible for converting big number values into decimal string representations, a critical operation in cryptographic computations where large integers are commonly processed. The flaw manifests in the function's improper validation of division results during the conversion process, creating a potential pathway for malicious exploitation that can affect systems relying on OpenSSL for secure communications.
The technical nature of this vulnerability stems from a lack of proper bounds checking during arithmetic operations within the big number library. When the BN_bn2dec function processes large integers, it performs division operations to extract individual digits for conversion to decimal format. The insufficient validation of these division results means that under certain conditions, the function may attempt to write data beyond the allocated memory boundaries. This out-of-bounds write condition creates a predictable crash scenario that can be exploited by remote attackers to cause denial of service attacks against systems utilizing vulnerable OpenSSL versions. The vulnerability operates at the level of the cryptographic library's internal arithmetic operations and represents a classic example of improper input validation that can lead to memory corruption issues.
The operational impact of CVE-2016-2182 extends beyond simple denial of service, as the vulnerability could potentially enable more sophisticated attacks depending on the specific implementation details and system configurations. Remote attackers capable of sending specially crafted data to systems using vulnerable OpenSSL versions could trigger application crashes that disrupt service availability, effectively creating a denial of service condition. The unspecified other impacts mentioned in the vulnerability description suggest that under certain circumstances, the memory corruption could potentially be exploited to achieve arbitrary code execution, making this vulnerability particularly concerning for systems handling sensitive data or operating in high-security environments. The vulnerability affects all OpenSSL versions prior to 1.1.0, representing a significant portion of systems that were widely deployed during the period when this vulnerability existed.
Mitigation strategies for CVE-2016-2182 primarily focus on upgrading to OpenSSL version 1.1.0 or later, where the division result validation has been properly implemented. System administrators should prioritize updating their OpenSSL installations to address this vulnerability, as the fix involves correcting the underlying validation logic in the BN_bn2dec function. Additionally, organizations should implement network monitoring to detect potential exploitation attempts and consider implementing additional security controls such as intrusion detection systems that can identify unusual patterns of data processing that might indicate exploitation attempts. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and could potentially map to ATT&CK technique T1499.004 for network denial of service attacks, emphasizing the need for comprehensive security measures beyond simple patching to protect against potential exploitation attempts.